Catalysts Useful for the Alkylation of Aromatic Hydrocarbons

ABSTRACT

A catalyst useful for the alkylation or transalkylation of aromatic compounds is disclosed. The catalyst is an acid-treated zeolitic catalyst produced by a process including contacting an acidic zeolitic catalyst comprising surface non-framework aluminum and framework aluminum with an organic dibasic acid at a catalyst to acid weight ratio in the range from about 2:1 to about 20:1 and at a temperature in the range from about 50° C. to about 100° C. to selectively remove at least a portion of the surface non-framework aluminum. The resulting catalyst may have a measured first-order rate constant, k cum , for the alkylation of benzene with propylene to form cumene, of at least 2.0 cm 3 /s g.

BACKGROUND OF DISCLOSURE

1. Field of the Disclosure

Embodiments disclosed herein relate generally to a process for thealkylation or transalkylation of aromatic compounds with olefins,alcohols and/or alkyl halides. In another aspect, embodiments disclosedherein relate to a process for the production of catalysts useful forthe alkylation or transalkylation of aromatic compounds.

2. Background

Alkylation refers generally to a type of chemical reaction resulting inaddition of an alkyl group to an organic compound. Olefins, such asethylene, propylene, and butylenes, are well-known alkylating agents,frequently used in synthesis of alkylated derivatives. Alkylation ofbenzene is a commercially important process, used to increase the octanerating of fuel and to produce valuable chemical feedstocks. For example,alkylation of benzene with ethylene may be used to produce ethylbenzene,which may be subsequently converted to styrene. Similarly, alkylation ofbenzene with propylene may be used to produce cumene, which may besubsequently converted to phenol and acetone.

A typical benzene alkylation reaction is shown below:

Alkylation technology, still widely employed in the petrochemicalindustry, involves the use of a catalyst based on phosphoric acid. Newertechnology utilizes non-polluting, non-corrosive, regenerable materials,such as zeolitic molecular sieve catalysts. U.S. Pat. Nos. 4,371,714 and4,469,908 disclose straight pass alkylation of aromatic compounds usingmolecular sieve catalysts in fixed beds. However, there are two mainproblems arising from the use of zeolitic catalysts in alkylationreactions, namely a rapid deactivation of the zeolitic catalyst due tocoking and poisoning and a higher yield of polyalkylated by-products.Other patents discussing use of zeolitic catalysts for alkylation andtransalkylation may include U.S. Pat. Nos. 5,118,897, 4,083,886, and4,891,458, among others.

Zeolitic materials, both natural and synthetic, have been demonstratedto have catalytic properties for various types of hydrocarbonconversion, including alkylation as mentioned above. It is oftenadvantageous to dealuminate these materials in order to improve theirprocess performance. Performance measures typically improved followingdealumination include product selectivity, product quality and catalyststability.

Conventional techniques for zeolite dealumination include hydrothermaltreatment, mineral acid treatment with HCl, HNO₃, and H₂SO₄, andchemical treatment with SiCl₄ or ethylenediaminetetraacetic acid (EDTA).The treatments are limited, in many cases, in the extent ofdealumination by the onset of crystal degradation and loss of sorptioncapacity. U.S. Pat. No. 4,419,220 discloses that dealumination ofzeolite Beta via treatment with HCl solutions is limited to SiO₂/Al₂O₃ratios of about 200 to 300 beyond which significant losses to zeolitecrystallinity are observed.

U.S. Pat. No. 3,442,795 describes a process for preparing highlysiliceous zeolite-type materials from crystalline aluminosilicates bymeans of a solvolysis, e.g. hydrolysis, followed by a chelation. In thisprocess, the acid form of a zeolite is subjected to hydrolysis, toremove aluminum from the aluminosilicate. The aluminum can then bephysically separated from the aluminosilicate by the use of complexingor chelating agents such as ethylenediaminetetraacetic acid orcarboxylic acid, to form aluminum complexes that are readily removablefrom the aluminosilicate. The examples are directed to the use of EDTAto remove alumina.

EP 0 259 526 B1 discloses the use of dealumination in producing ECR-17.The preferred dealumination method involves a combination of steamtreatment and acid leaching, or chemical treatments with siliconhalides. The acid used is preferably a mineral acid, such as HCl, HNO₃or H₂SO₄, but may also be weaker acids such as formic, acetic, citric,oxalic, tartaric acids and the like.

U.S. Pat. No. 5,310,534 discloses the dealumination of zeolites usingstrong inorganic and organic acids, such as formic acid, trichloroaceticacid, trifluoracetic acid, hydrochloric acid, sulfuric acid, and nitricacid.

U.S. Pat. No. 5,874,647 discloses a process for preparing a zeolitecatalyst including hydrothermally treating a catalyst with a gasincluding water and inert components at an elevated temperature followedby treating of the catalyst with an acid, such as nitric, oxalic,hydrochloric, methanesulfonic, fluorosulfonic, and hydrofluoric acid.

U.S. Pat. No. 6,620,402 discloses a process including the dealuminationof zeolites by removal of the zeolite framework or crystal structure,such as obtained by removal of the Al⁺³ ions. Dealuminizing agentsinclude mineral acids, polyvalent acids, and chelating agents, such asan ammonium-containing agent.

Other various patents describing aluminum extraction from a zeolite mayinclude U.S. Pat. Nos. 4,954,243, 5,242,676, 5,200,168, 5,304,695,5,567,666, 5,929,295, 6,025,293, 5,723,710, and 5,321,194.

Conditions used in many prior art dealumination processes may result inloss of high acidity framework aluminum sites within the catalyst, whichadditionally results in a loss of catalyst activity. Accordingly, thereexists a need for dealumination processes that may selectively removeonly a portion of the alumina, non-framework aluminum, enhancing theaccessibility to the strong acidic sites contained in the zeoliticstructure.

SUMMARY OF THE DISCLOSURE

In one aspect, embodiments disclosed herein relate to a method forimproving the activity of acidic zeolitic catalysts, the methodincluding: contacting an acidic zeolitic catalyst comprising surfacenon-framework aluminum and framework aluminum with an organic dibasicacid at a catalyst to acid weight ratio in the range from about 2:1 toabout 20:1 and at a temperature in the range from about 50° C. to about100° C. for a duration of up to about 2 hours to selectively remove atleast a portion of the surface non-framework aluminum, thereby forming aselectively dealuminated zeolitic catalyst. The selectively dealuminatedzeolitic catalyst may have a measured first-order rate constant,k_(cum), for the alkylation of benzene with propylene to form cumene, ofat least 2.0 cm³/s g.

In another aspect, embodiments disclosed herein relate to a process forthe alkylation or transalkylation of aromatic hydrocarbons, including:contacting a) at least one C₆₊ aromatic hydrocarbon and b) at least oneof an olefin, an alcohol, and an alkyl halide with c) an acid-treatedzeolitic catalyst under conditions of temperature and pressure toproduce at least one of an alkylate product and a transalkylate product;wherein the acid-treated zeolitic catalyst is produced by a processincluding contacting an acidic zeolitic catalyst comprising surfacenon-framework aluminum and framework aluminum with an organic dibasicacid at a catalyst to acid weight ratio in the range from about 2:1 toabout 20:1 and at a temperature in the range from about 50° C. to about100° C. to selectively remove at least a portion of the surfacenon-framework aluminum.

In another aspect, embodiments disclosed herein relate to a catalystuseful for the alkylation or transalkylation of aromatic compounds, thecatalyst comprising an acid-treated zeolitic catalyst produced by aprocess including: contacting an acidic zeolitic catalyst comprisingsurface non-framework aluminum and framework aluminum with an organicdibasic acid at a catalyst to acid weight ratio in the range from about2:1 to about 20:1 and at a temperature in the range from about 50° C. toabout 100° C. to selectively remove at least a portion of the surfacenon-framework aluminum.

Other aspects and advantages will be apparent from the followingdescription and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 presents test results comparing activity of selectivelydealuminated zeolitic catalysts according to embodiments disclosedherein with untreated zeolitic catalysts.

DETAILED DESCRIPTION

In one aspect, embodiments herein relate to a process for the alkylationor transalkylation of aromatic compounds with olefins, alcohols and/oralkyl halides. In another aspect, embodiments disclosed herein relate toa process for the production of catalysts useful for the alkylation ortransalkylation of aromatic compounds.

Catalysts useful in embodiments disclosed herein include acidic zeoliticcatalysts, such as silica-aluminas and aluminosilicates, that have beentreated with an organic dibasic acid to selectively remove a portion ofthe aluminum from the catalyst. Aluminum-containing catalysts usefulherein may be characterized as having a crystalline framework structurecomposed of an assembly of silicon and aluminum atoms, each surroundedby a tetrahedron of shared oxygen atoms, and a precisely defined porestructure. Exchangeable cations may be present in the pores. In additionto the framework aluminum, aluminum containing catalysts useful inembodiments disclosed herein may have non-framework or extra-frameworkaluminum that is not integral with the crystalline framework structure.Treatment of acidic zeolitic catalysts with organic dibasic acidsaccording to methods described herein may selectively remove thenon-framework aluminum, thus increasing the overall acidity of thecatalyst. In some embodiments, the acid treatment may be performed underconditions such that only non-framework aluminum is removed from thecatalyst, extracting essentially no aluminum from the framework of thecatalyst.

The catalysts may also contain one or more optional elements, includingtitanium, zirconium, hafnium, tantalum, and niobium, in an amount fromabout 0 weight percent up to about 10 weight percent; from about 0.01weight percent to about 3 weight percent in other embodiments. Theseoptional elements may be incorporated into the catalyst material priorto selective dealumination or introduced to the material after selectivedealumination.

The selectively dealuminated catalysts according to embodimentsdisclosed herein may be prepared by contacting an acidic zeoliticcatalyst comprising surface non-framework aluminum and frameworkaluminum with an organic dibasic acid to selectively remove at least aportion of the surface non-framework aluminum. The amount of organicdibasic acid required for the selective dealumination may depend on thedetailed composition of a given acidic zeolitic catalyst and it physicalproperties. In general, the amount of organic dibasic acid used duringthe treating step may be at a catalyst to acid weight ratio in the rangefrom about 1.5:1 to about 20:1 in some embodiments. In otherembodiments, the catalyst to acid ratio may be in the range from about2:1 to about 20:1; from about 2:1 to about 15:1 in other embodiments;from about 2.5:1 to about 12:1 in other embodiments; from about 3.5:1 toabout 10:1 in other embodiments; and from about 6:1 to about 8:1 in yetother embodiments.

The acidic zeolitic catalyst may be contacted with the organic dibasicacid solution for a time ranging from 5 minute to 2 hours in someembodiments; from 30 minutes to 90 minutes in other embodiments. Theselective dealumination of acidic zeolitic catalysts may be performed ina single step or multiple steps. The selective dealumination may beperformed at relatively mild conditions, such as at a temperature in therange from about 50° C. to about 100° C. in some embodiments; at atemperature in the range from about 65° C. to about 90° C. in otherembodiments. During contact with the organic dibasic acid, the slurrymay be stirred continuously or intermittently.

Following contact with the organic dibasic acid for the selectivedealumination, the excess solution in the treatment vessel should bedrained, and the selectively dealuminated catalyst may be washed withsufficient amounts of clean, deionized water. The catalyst may then bedried, such as at a temperature in the range from about 80° C. to about150° C.

Acidic zeolitic catalysts that may be selectively dealuminated accordingto embodiments disclosed herein may include natural and syntheticzeolites. Acidic crystalline zeolitic structures useful in embodimentsdisclosed herein may be obtained by the building of a three dimensionalnetwork of AlO₄ and SiO₄ tetrahedra linked by the sharing of oxygenatoms. The framework thus obtained contains pores, channels and cages orinterconnected voids. As trivalent aluminum ions replace tetravalentsilicon ions at lattice positions, the network bears a net negativecharge, which must be compensated for by counterions (cations). Thesecations are mobile and may occupy various exchange sites depending ontheir radius, charge or degree of hydration, for example. They can alsobe replaced, to various degrees, by exchange with other cations. Becauseof the need to maintain electrical neutrality, there is a direct 1:1relationship between the aluminum content of the framework and thenumber of positive charges provided by the exchange cations. When theexchange cations are protons, the zeolite is acidic. The acidity of thezeolite is therefore determined by the amount of proton exchanged forother cations with respect to the amount of aluminum.

Zeolitic catalysts that may be used in some embodiments disclosed hereinmay include large pore size zeolites, intermediate pore size zeolites,and small pore size zeolites. These zeolites are described in “Atlas ofZeolite Structure Types,” eds. W. H. Meier and D. H. Olson,Butterworth-Heineman, Third Edition, 1992, which is hereby incorporatedby reference. A large pore zeolite generally has a pore size greaterthan about 7 Å and includes for example LTL, VFI, MAZ, MEI, FAU, EMT,OFF, BEA, and MOR structure type zeolites (IUPAC Commission of ZeoliteNomenclature). Examples of large pore zeolites, include, for example,mazzite, mordenite, offretite, zeolite L, VPI-5, zeolite Y, zeolite X,omega, Beta, ZSM-3, ZSM-4, ZSM-18, and ZSM-20. An intermediate pore sizezeolite generally has a pore size from about 5 Å, to about 7 Å andincludes for example, MFI, MFS, MEL, MTW, EUO, MTT, HEU, FER, and TONstructure type zeolites (IUPAC Commission of Zeolite Nomenclature).Examples of intermediate pore size zeolites, include ZSM-5, ZSM-12,ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50, silicalite, andsilicalite 2. A small pore size zeolite generally has a pore size fromabout 3 Å to about 5.0 Å and includes for example, CHA, ERI, KFI, LEV,and LTA structure type zeolites (IUPAC Commission of ZeoliteNomenclature). Examples of small pore zeolites include ZK-4, ZK-14,ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, erionite, chabazite, zeolite T,gemlinite, and clinoptilolite.

Clay or amorphous catalysts including silica-alumina and fluoridedsilica-alumina may also be used. Further discussion of alkylationcatalysts may be found in U.S. Pat. Nos. 5,196,574; 6,315,964 and6,617,481. Various types of zeolitic catalysts may be used foralkylation as well as other types of catalytic refinery processes. FCCprocesses may utilize at least one of a type Y, Beta, and ZSM-5, forexample. The FCC zeolitic catalyst typically contains three parts: thezeolite, typically about 30 to 50 wt. % of the catalyst particle, anactive matrix, and a binder. In one embodiment, the particle size of theFCC catalyst may be between 50 and 60 microns. In another embodiment,the zeolitic catalyst may initially come in ammonium form, which may beconverted to the H⁺ form by heating at over 300° C. before being used asan alkylation catalyst. One must take care not to overheat the catalystprior to alkylation, because excessive temperature may dealuminate thezeolite and shrink the ring structures, which may reduce the activityfor alkylation. In addition to zeolitic catalyst, inorganic catalyst,such as sulfated zirconia or tungstated zirconia, may be used foralkylation as well. Other useful zeolitic catalysts may include ZSM-22,ZSM-23, MCM-22, and MCM-49.

In some embodiments, suitable catalysts for alkylation andtransalkylation may include metal stabilized catalysts. For example,such catalysts may include a zeolite component, a metal component, andan inorganic oxide component. The zeolite may be a pentasil zeolite,which include the structures of MFI, MEL, MTW, MTT and FER (IUPACCommission on Zeolite Nomenclature), MWW, a beta zeolite, or amordenite. The metal component typically is a noble metal or base metal,and the balance of the catalyst may be composed of an inorganic oxidebinder, such as alumina. Other catalysts having a zeolitic structurethat may be used in embodiments disclosed herein are described in, forexample, U.S. Pat. No. 7,253,331, which is hereby incorporated byreference.

Prior to or following selective dealumination, the acidic zeoliticcatalyst may be composited with a porous matrix material, such asalumina, silica, titania, zirconia, silica-alumina, silica-magnesia,silica-zirconia, silica-thoria, silica-beryllia, silica-titania as wellas ternary compositions, such as silica-alumina-thoria,silica-alumina-zirconia, silica-alumina-magnesia, andsilica-magnesia-zirconia. The matrix may be in the form of a cogel. Therelative proportions of zeolite component and inorganic oxide gel matrixmay vary widely with the zeolite content ranging from between 1 to 99,more usually 5 to 80, percent by weight of the composite.

Organic dibasic acids useful for selective dealumination processesaccording to embodiments disclosed herein may include variousdicarboxylic acids. Suitable acids may include oxalic, malonic,succinic, glutaric, adipic, tartaric, maleic, phthalic, or mixturesthereof. Other useful carboxylic acids may include 1,2-cyclopentanedicarboxylic acid, fumaric acid, itaconic acid, phthalic acid,terephthalic acid, phenylmalonic acid, hydroxyphtalic acid,dihydroxyfumaric acid, tricarballylic acid, andbenzene-1,3,5-tricarboxylic acid. The dicarboxylic acid may be used insolution, such as an aqueous dicarboxylic acid solution. Tricarboxylicacids such as citric acid and higher polycarboxylic acids can also beused. More than one acid treatment step may be used to attain thedesired selective dealumination in the processes disclosed herein.

As a result of dealumination at conditions suitable to selectivelydealuminate only non-framework aluminum, catalysts according toembodiments disclosed herein may exhibit exceptionally high activity foralkylation and transalkylation reactions, such as the alkylation ofbenzene with propylene to form cumene. For example, selectivelydealuminated catalysts according to embodiments disclosed herein mayhave an activity, as measured under controlled test conditions asdescribed in the test procedures below (Examples), where the first-orderrate constant k_(cum), is at least 2 cm³/s g. In other embodiments, thefirst-order rate constant k_(cum), may be at least 2.25 cm³/s g; atleast 2.5 cm³/s g in other embodiments; at least 3 cm³/s g in otherembodiments; at least 3.25 cm³/s g in other embodiments; at least 3.5cm³/s g in other embodiments; and at least 4 cm³/s g in otherembodiments.

For example, in some embodiments, a beta zeolite may be selectivelydealuminated according to embodiments disclosed herein, resulting in aselectively dealuminated catalyst having a first-order rate constantk_(cum), of at least 2 cm³/s g; at least 2.1 cm³/s g in otherembodiments; at least 2.2 cm³/s g in other embodiments; at least 2.5cm³/s g in other embodiments; and at least 3 cm³/s g in otherembodiments.

As another example, in some embodiments, a high performance beta zeolitemay be selectively dealuminated according to embodiments disclosedherein, resulting in a selectively dealuminated catalyst having afirst-order rate constant k_(cum), of at least 2.5 cm³/s g; at least 3cm³/s g in other embodiments; at least 3.5 cm³/s g in other embodiments;at least 3.75 cm³/s g in other embodiments; and at least 4 cm³/s g inother embodiments.

Selective dealumination of catalysts according to embodiments disclosedherein, may thus be produced by a process including: forming an aqueoussolution of the organic dibasic acid; admixing the acidic zeoliticcatalyst with the aqueous solution for the contacting; separating theacid-contacted zeolitic catalyst from the aqueous solution; washing theacid-contacted catalyst to remove any excess organic dibasic acid; anddrying the washed catalyst at a temperature in the range from about 80°C. to about 150° C.

Further, due to the treatment conditions and acid:catalyst dosages usedherein, additional processing steps commonly used to dealuminate zeolitecatalysts may be eliminated. For example, many prior art dealuminationprocesses include hydrothermal treatment of the zeolite, or otherpre-treatment steps, prior to acid treatment. Selective dealuminationaccording to embodiments disclosed herein may be performed without suchpre-treatment steps while resulting in a catalyst having anexceptionally high activity. Thus, processes to manufacture catalystsaccording to embodiments disclosed herein may be performed absent ahydrothermal treatment step or other common pre-treatment steps used forthe dealumination of a zeolite.

The above-described selectively dealuminated catalysts may be used forthe alkylation or transalkylation of aromatic compounds with variousalkylation agents, including olefins, alcohols, and alkyl halides. Suchcatalysts may additionally find use in processes for the alkylation ofisoparaffins with olefins and/or alcohols, as well as in fluid catalyticcracking (FCC) processes or hydrocracking processes.

In some embodiments of the alkylation and transalkylation processesdescribed herein, olefins are reacted with aromatic hydrocarbons, suchas benzene, to form an alkylate or transalkylate product. In someembodiments, olefins for the alkylation or transalkylation of aromatichydrocarbon are those containing 2 to 6 carbon atoms. In otherembodiments, olefins for the alkylation or transalkylation of aromatichydrocarbon are those containing 2 to 4 carbon atoms, such as ethylene,propylene, butene-1, trans-butene-2 and cis-butene-2, or mixturesthereof.

The olefin feed streams used in various embodiments disclosed herein mayalso contain certain impurities, such as the corresponding C₂ to C₄paraffins. Typically, the impurities, including dienes, acetylenes,water, sulfur compounds or nitrogen compounds which may be present inthe olefin feedstock stream, are removed prior to the alkylation andtransalkylation reaction to prevent rapid catalyst deactivation. In somecases, however, it may be desirable to add, in a controlled fashion,small amounts of water or nitrogen compounds to optimize catalyticproperties.

In other embodiments, olefins useful in embodiments disclosed herein mayinclude up to 20 carbon atoms. For example, olefins having greater than6 carbon atoms may be used.

Alcohols useful in embodiments disclosed herein may include C₁ to C₆primary and secondary alcohols. The term “alcohol” includes lower alkylalcohols capable of forming azeotropes with the saturated andunsaturated hydrocarbons, in particular the C₃ to C₇ hydrocarbons, ofthe hydrocarbon feedstock. Examples of alcohols useful in embodimentsdisclosed herein include methanol, ethanol, n-propanol, i-propanol,n-butanol, i-butanol and t-butanol. In some embodiments, methanol may beused in combination with one or more of the C₂₊ alcohols.

Alkyl halides useful in embodiments disclosed herein may include mono-or poly-halogenated C₂ to C₆ hydrocarbons, such as alkyl chlorides andalkyl bromides. For example, alkyl halides useful in embodimentsdisclosed herein may include methyl, ethyl, propyl, and butyl halides,their higher homologs, and their isomers.

In embodiments of the alkylation processes disclosed herein, ahydrocarbon feedstock containing aromatics, such as benzene, is reactedwith olefins in the presence of an alkylation catalyst to form alkylbenzenes, which may be useful as specialty chemical feedstocks or as ahigh-octane gasoline component. In particular, one embodiment describedherein involves reaction of benzene with a C₂ to C₄ olefin to formmonoalkylate product in the presence of an alkylation catalyst. Theprecise process steps and process conditions may vary depending upon thecatalyst system used. In another embodiment, a heterogeneous slurrycatalyst is used to facilitate the alkylation reaction. For the purposeof illustration and not a limitation of the process, severalrepresentative alkylation reactions of olefins with benzene are providedas follows:

ethylene+benzene→methylbenzene   1)

propylene+benzene→isopropylbenzene (cumene)   2)

n-butylene+benzene→butylbenzene   3)

isobutylene+benzene→isobutylbenzene   4)

In addition to the monoalkylate product, alkylation reactions typicallyyield other undesirable byproducts in the form of heavy hydrocarbons,including but not limited to, polyalkylate, heavy flux oil (includingcomponents that will not transalkylate), and polymerized feed olefins.

Transalkylation reactions may be used to produce monoalkylate product byreacting benzene with polyalkylate. When transalkylation is desired, thetransalkylating agent is a polyalkylate aromatic hydrocarbon containingtwo or more alkyl groups that each may have from 2 to about 4 carbonatoms. For example, suitable polyalkylate aromatic hydrocarbons includedi-, tri- and tetra-alkyl aromatic hydrocarbons, such as diethylbenzene,triethylbenzene, diethylmethylbenzene (diethyltoluene),diisopropylbenzene, triisopropylbenzene, diisopropyltoluene,dibutylbenzene, and the like. In one particular embodiment, thepolyalkylate aromatic hydrocarbon is diisopropylbenzene, which reactswith benzene to form cumene (isopropylbenzene).

Reaction products that may be obtained from the transalkylation processof benzene include, but are not limited to, ethylbenzene from thereaction of benzene with either ethylene or polyethylbenzenes; cumenefrom the reaction of benzene with propylene or polyisopropylbenzenes;ethyltoluene from the reaction of toluene with ethylene orpolyethyltoluenes; cymenes from the reaction of toluene with propyleneor polyisopropyltoluenes; and sec-butylbenzene from the reaction ofbenzene and n-butylene or polybutylbenzenes. For the purpose ofillustration and not a limitation of the process, several representativetransalkylation reactions of polyalkylate with benzene are provided asfollows:

diethylbenzene+benzene→2 ethylbenzene   1)

di-isopropylbenzene+benzene→2 isopropylbenzene (cumene)   2)

dibutylbenzene+benzene→2 butylbenzene   3)

Various types of reactors can be used in the process of alkylation aswell as transalkylation. Selection of the type of reactor for use inalkylation or transalkylation reaction may depend on a number offactors, including the desired mode of operation, throughput volume, andreaction control parameters, such as residence time and product yield.

Large scale industrial processes typically use continuous flow reactors,either as fixed bed or as moving bed reactors. Moving bed reactorstypically operate either with concurrent or countercurrent catalyst,olefin, and hydrocarbon flows. These reactors may contain a singlecatalyst bed or multiple beds and may be equipped for the interstageaddition of olefins and interstage cooling. Interstage olefin additionand more nearly isothermal operation enhance product quality andcatalyst life. A moving bed reactor makes possible the continuousremoval of spent catalyst for regeneration and replacement by fresh orregenerated catalysts.

In a moving bed reactor, alkylation is completed in a relatively shortreaction zone following the introduction of olefin. Ten to thirtypercent of the reacting aromatic molecules may be alkylated more thanonce. Transalkylation is a slower reaction which occurs both in thetransalkylation and the alkylation reaction zones. If transalkylationproceeds to equilibrium, better than 90 wt % selectivity tomonoalkylated product is generally achieved. Thus, transalkylationincreases the yield of monoalkylated product by reacting thepolyalkylated products with benzene.

In the selective monoalkylation of aromatics by olefins as catalyzed bythe selectively dealuminated catalysts according to embodimentsdisclosed herein, the olefins, alcohols, and alkyl halides may containfrom 2 up to at least 20 carbon atoms, and may be branched or linear,either terminal or internal. Thus, the specific nature of the alkylatingagent is not particularly important.

Benzene is by far the most important representative of the alkylatablearomatic compounds which may be used in embodiments disclosed herein.More generally the aromatic compounds may be selected from the groupconsisting of benzene, naphthalene, anthracene, phenanthrene, andsubstituted derivatives thereof. The most important class ofsubstituents found on the aromatic nucleus of alkylatable aromaticcompounds are alkyl moieties containing from 1 up to about 20 carbonatoms. Another important substituent is the hydroxyl moiety as well asthe alkoxy moiety whose alkyl group also contains from 1 up to 20 carbonatoms. Where the substituent is an alkyl or alkoxy group, a phenylmoiety also can be substituted on the paraffinic chain. Althoughunsubstituted and monosubstituted benzenes, naphthalenes, anthracenes,and phenanthrenes are most often used in the practice of this invention,polysubstituted aromatics also may be employed. Examples of suitablealkylatable aromatic compounds in addition to those cited above includebiphenyl, toluene, xylene, ethylbenzene, propylbenzene, butylbenzene,pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, and so forth;phenol, cresol, anisole, ethoxy-, propoxy-, butoxy-, pentoxy-,hexoxybenzene, and so forth.

Alkylation conditions may include pressures in the range between about200 and about 1,000 psig (1379-6985 kPa) but usually is in a rangebetween about 300-600 psig (2069-4137 kPa). Representative alkylationtemperatures include a range of between 200-250° C. for alkylation ofbenzene with ethylene and temperatures of 90-200° C. for the alkylationof benzene by propylene. The temperature range appropriate foralkylation of the alkylatable aromatic compounds of our invention withthe olefins in the C2-C20 range is between about 60 and about 400° C.,with the most usual temperature range being between about 90 and 250° C.

The ratio of alkylatable aromatic compound to alkylating agent used inthe process may depend upon the degree of selective monoalkylationdesired as well as the relative costs of the aromatic and olefiniccomponents of the reaction mixture. For alkylation of benzene bypropylene, benzene-to-olefin ratios may be as low as about 1 and as highas about 10, with a ratio of 2.5-8 being preferred. Where benzene isalkylated with ethylene a benzene-to-olefin ratio between about 1:1 and8:1 is preferred. For detergent range olefins of C6-C20, abenzene-to-olefin ratio of between 5:1 up to as high as 30:1 isgenerally sufficient to ensure the desired monoalkylation selectivity,with a range between about 8:1 and about 20:1 even more highly desired.

As previously mentioned, catalysts according to embodiments disclosedherein may also be used to catalyze transalkylation as well asalkylation. By “transalkylation” is meant that process where an alkylgroup on one aromatic nucleus is intermolecularly transferred to asecond aromatic nucleus. The transalkylation of particular interest hereis one where one or more alkyl groups of a polyalkylated aromaticcompound is transferred to a nonalkylated aromatic compound, and isexemplified by reaction of diisopropylbenzene with benzene to afford twomolecules of cumene. Thus, transalkylation often is utilized to add tothe selectivity of a desired selective monoalkylation by reacting thepolyalkylates invariably formed during alkylation with nonalkylatedaromatic to form additional monoalkylated products. For the purposes ofthis section the polyalkylated aromatic compounds are those formed inthe alkylation of alkylatable aromatic compounds with olefins asdescribed above, and the nonalkylated aromatic compounds are benzene,naphthalene, anthracene, and phenanathrene. The reaction conditions fortransalkylation are similar to those for alkylation, with temperaturesbeing in the range of 100 to about 250° C., pressures in the range of100 to about 750 psig, and the molar ratio of unalkylated aromatic topolyalkylated aromatic being in the range from about 1 to about 10.Examples of polyalkylated aromatics which may be reacted with, e.g.,benzene as the nonalkylated aromatic include diethylbenzene,diisopropylbenzene, dibutylbenzene, triethylbenzene,triisopropylbenzene, and so forth.

EXAMPLES Testing Procedures for Cumene Application

The catalytic activity of the zeolite beta catalysts was evaluated inthe reaction of benzene alkylation with propylene to form cumene. Thetest reactor was a recirculating differential fixed bed reactor (⅞ inchID SS tube) and the test conditions were a pressure of 350 psig, atemperature of 170° C., and a recirculation rate of 200 grams/min. Thetest feed contained 0.35-0.45 wt. % propylene dissolved in benzene witha feed rate of 6.0 grams/min. The catalyst charge was 0.7 gram with aparticle size of 12-20 mesh derived from 1.6 mm extrudates containing 80wt % zeolite and 20 wt % binders. The catalyst was dried two hours at350° C. before loading the reactor. The test was carried out for 7 to 8hours with samples taken every 30 minutes for analysis by gaschromatography (GC). The first-order reaction rate constant k, wascalculated to represent catalyst activity for the alkylation of benzenewith propylene to form cumene.

Catalyst Preparation Comparative Example 1 Commercial Beta

The Zeolite beta catalyst used in this example and Examples 1-7 wasobtained from Zeolyst International Co. of Valley Forge, Pa. Thecatalyst as received was 1.6 mm extrudates containing 80 wt % zeoliteand was resized to 12-20 mesh particles. A portion of the catalystparticles was tested for catalytic activity for alkylation of benzenewith propylene to cumene using the procedure described above and theother portion of the catalyst particles was first subjected to the acidtreatment as described in Example 1-7 and then evaluated, the results ofwhich are listed in Table 1 and illustrated in FIG. 1.

Example 1

An aqueous solution formed by dissolving 0.50 gram of oxalic aciddihydrate in 200 mL of deionized (DI) water was heated to 70° C. Then5.0 grams of catalyst particles from Comparative Example 1 were added tothe solution and the resulting mixture was held at 70° C. for one hourwith stirring. After cooling this mixture to 25° C., the solid materialswere collected by vacuum filtration. The solids thus obtained were addedto 500 mL of DI water and the resulting mixture was heated to 70° C. andheld at this temperature for one hour with stirring. Finally, the solidswere collected by vacuum filtration and oven dried overnight at 120° C.

Example 2

An aqueous solution formed by dissolving 1.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 1 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 3

An aqueous solution formed by dissolving 2.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70% Then 5.0 grams ofcatalyst particles from Comparative Example 1 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 4

An aqueous solution formed by dissolving 3.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 1 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 5

An aqueous solution formed by dissolving 10.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 1 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 6

An aqueous solution formed by dissolving 25.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 1 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 7

An aqueous solution formed by dissolving 0.87 gram of malonic acid in200 mL of DI water was heated to 70° C. Then 5.0 grams of catalystparticles from Comparative Example 1 were added to the solution and theresulting mixture was held at 70° C. for one hour with stirring. Aftercooling this mixture to 25° C., the solid materials were collected byvacuum filtration. The solids thus obtained were added to 500 mL of DIwater and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

TABLE 1 Acid Treatment k_(cum) Example Acid Catalyst:Acid (w/w) (cm³C₃=/s-g) Comparative — — 1.1 Example 1 1 Oxalic Acid 14.0 2.1 2 OxalicAcid 7.0 3.3 3 Oxalic Acid 3.5 2.8 4 Oxalic Acid 2.3 2.5 5 Oxalic Acid0.7 1.2 6 Oxalic Acid 0.3 0.9 7 Malonic Acid 5.7 2.0

Comparative Example 2 High Performance Beta

The high performance beta (“HP” Beta) used in this example and Examples8-19 was prepared in accordance with the method set forth in U.S. Pat.No. 6,809,055 in a form of 1.6 mm extrudates with 80 wt % zeolite and 20wt % binder. The extrudates were resized to 12-20 mesh for reactorevaluation and for the acid treatment described in Examples 8-19. Thetesting results of this sample along with the acid-treated samples aresummarized in Table 2.

Example 8

An aqueous solution formed by dissolving 0.50 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 2 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 9

An aqueous solution formed by dissolving 1.0 gram of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 2 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 10

An aqueous solution formed by dissolving 2.0 grams of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 2 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 11

An aqueous solution formed by dissolving 25.0 grams of oxalic aciddihydrate in 200 mL of DI water was heated to 70° C. Then 5.0 grams ofcatalyst particles from Comparative Example 2 were added to the solutionand the resulting mixture was held at 70° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 12

An aqueous solution formed by dissolving 2.0 grams of oxalic aciddihydrate in 200 mL of DI water was heated to 85° C. Then 5.0 grams ofcatalyst particles from Comparative Example 2 were added to the solutionand the resulting mixture was held at 85° C. for one hour with stirring.After cooling this mixture to 25° C., the solid materials were collectedby vacuum filtration. The solids thus obtained were added to 500 mL ofDI water and the resulting mixture was heated to 85° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 13

An aqueous solution was formed by dissolving 2.0 grams of oxalic aciddihydrate in 200 mL of DI water. Then 5.0 grams of catalyst particlesfrom Comparative Example 2 were added to the solution and the resultingmixture was stirred one hour at 22° C. The solid materials werecollected by vacuum filtration, washed with 500 mL of DI water, and ovendried overnight at 120° C.

Example 14

An aqueous solution was formed by dissolving 2.0 grams of oxalic aciddihydrate in 200 mL of DI water. Then 5.0 grams of catalyst particlesfrom Comparative Example 2 were added to the solution and the resultingmixture was stirred six hours at 22° C. The solid materials werecollected by vacuum filtration, washed with 500 mL of DI water, and ovendried overnight at 120° C.

Example 15

An aqueous solution (200 mL) containing 3.5 wt % HNO3 was heated to 70°C. Then 5.0 gram of catalyst particles from Comparative Example 2 wereadded to the solution and the resulting mixture was stirred at 70° C.for one hour. After cooling this mixture to 25° C., the solid materialswere collected by vacuum filtration. The solids thus obtained were addedto 500 mL of DI water and the resulting mixture was heated to 70° C. andheld at this temperature for one hour with stirring. Finally, the solidswere collected by vacuum filtration and oven dried overnight at 120° C.

Example 16

An aqueous solution (200 mL) containing 0.7 wt HNO₃ was heated to 70° C.Then 5.0 gram of catalyst particles from Comparative Example 2 wereadded to the solution and the resulting mixture was stirred at 70° C.for one hour. After cooling this mixture to 25° C., the solid materialswere collected by vacuum filtration. The solids thus obtained were addedto 500 mL of DI water and the resulting mixture was heated to 70° C. andheld at this temperature for one hour with stirring. Finally, the solidswere collected by vacuum filtration and oven dried overnight at 120° C.

Example 17

Catalyst particles (5.0 g) from Comparative Example 2 were added to anaqueous solution (200 mL) containing 0.7 wt % HNO₃ and the mixture wasstirred at 22° C. for one hour. Then the catalyst particles werecollected by vacuum filtration, washed with 500 mL of DI water, and ovendried overnight at 120° C.

Example 18

An aqueous solution formed by dissolving 1.35 grams of acetic acid in200 mL of DI water was heated to 70° C. Then 5.0 gram of catalystparticles from Comparative Example 2 were added to the solution and theresulting mixture was held at 70° C. for one hour with stirring. Aftercooling the mixture to 25° C., the solid materials were collected byvacuum filtration. The solids thus obtained were added to 500 mL of DIwater and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

Example 19

An aqueous solution formed by dissolving 0.87 gram of malonic acid in200 mL of DI water was heated to 70° C. Then 5.0 gram of catalystparticles from Comparative Example 2 were added to the solution and theresulting mixture was held at 70° C. for one hour with stirring. Aftercooling the mixture to 25° C., the solid materials were collected byvacuum filtration. The solids thus obtained were added to 500 mL of DIwater and the resulting mixture was heated to 70° C. and held at thistemperature for one hour with stirring. Finally, the solids werecollected by vacuum filtration and oven dried overnight at 120° C.

TABLE 2 Acid Treatment Conditions k_(cum) Catalyst:Acid Temperature Time(cm³ Example Acid (w/w) (° C.) (hr) C₃ ⁼/s-g) Comp. — — — — 2.0 Example2  8 Oxalic Acid 14.0 70 1 5.2  9 Oxalic Acid 7.0 70 1 10 10 Oxalic Acid3.5 70 1 7.1 11 Oxalic Acid 0.3 70 1 0.9 12 Oxalic Acid 3.5 85 1 3.8 13Oxalic Acid 3.5 22 1 2.2 14 Oxalic Acid 3.5 22 6 2.6 15 Nitric Acid 0.770 1 2.6 16 Nitric Acid 3.6 70 1 3.1 17 Nitric Acid 3.6 22 1 2.2 18Acetic Acid 3.7 70 1 2.2 19 Malonic 5.7 70 1 4.3 Acid

The test procedure and results for alkylation of linearalkylalkylbenzenes are shown below: Catalytic activity of the commercialbeta (same sample as used in Comparative Example 1) and acid treatedbeta (same sample as used in Example 2) was evaluated. All the runs werecarried out with a 1-liter autoclave equipped with a stirrer. For thealkylation of benzene with 1-dodecene, the reaction was carried out at140° C. with 1.25 g of catalyst, 112 g of benzene, and 12 g of1-dodecene. For the alkylation of benzene with pacolate, the reactionwas also carried out at 140° C., but with 0.625 g catalyst, 60 g ofbenzene, and 60 g of pacolate which contains 50 g of paraffins (C10-C14)and 6 g of olefins (C10-C14). The reaction mixtures were analyzed at2.5, 4.0, and 6.0 hr reaction time by GC and the conversions aresummarized in Table 3.

TABLE 3 Commercial Beta Acid-Treated Reaction % Olefin Beta % OlefinReaction Time (hr) Conversion Conversion Alkylation of benzene 2.5 63.877.0 with 1-dodecene 4.0 74.6 94.0 6.0 82.6 95.3 Alkylation of benzene2.5 54.0 69.4 with pacolate 4.0 67.9 86.6 6.0 73.5 91.4

As described above, embodiments disclosed herein provide for zeoliticcatalysts suitable for use in alkylation and transalkylation processes.The zeolitic catalysts are dealuminated at specified acid to catalystratios and reaction conditions to selectively remove at least a portionof the non-framework aluminum. In some embodiments, dealuminationprocesses according to embodiments disclosed herein may advantageouslyremove essentially only surface non-framework aluminum while leaving theframework aluminum intact. Selective dealumination according toembodiments disclosed herein may enhance the strong acid sites containedin the catalyst. Thus, selectively dealuminated catalysts according toembodiments disclosed herein may have active acidic sites more readilyaccessible for the desired aromatic alkylation and transalkylationreactions.

While the disclosure includes a limited number of embodiments, thoseskilled in the art, having benefit of this disclosure, will appreciatethat other embodiments may be devised which do not depart from the scopeof the present disclosure. Accordingly, the scope should be limited onlyby the attached claims.

What is claimed:
 1. A method for improving the activity of acidiczeolitic catalysts, the method comprising: contacting an acidic zeoliticcatalyst comprising surface non-framework aluminum and frameworkaluminum with an organic dibasic acid at a catalyst to acid weight ratioin the range from about 2:1 to about 20:1 and at a temperature in therange from about 50° C. to about 100° C. for a duration of up to about 2hours to selectively remove at least a portion of the surfacenon-framework aluminum, thereby forming a selectively dealuminatedzeolitic catalyst; wherein the selectively dealuminated zeoliticcatalyst has a measured first-order rate constant, k_(cum), for thealkylation of benzene with propylene to form cumene, of at least 2.0cm³/s g.
 2. The method of claim 1, further comprising: forming anaqueous solution of the organic dibasic acid; admixing the acidiczeolitic catalyst with the aqueous solution for the contacting;separating the acid-contacted zeolitic catalyst from the aqueoussolution; washing the acid-contacted catalyst to remove any excessorganic dibasic acid; and drying the washed catalyst at a temperature inthe range from about 80° C. to about 150° C.
 3. The method of claim 1,wherein the contacting a zeolitic catalyst with an organic dibasic acidremoves essentially no surface framework aluminum.
 4. The method ofclaim 1, wherein the catalyst to acid weight ratio is in the range fromabout 6:1 to about 8:1.
 5. The method of claim 4, wherein theselectively dealuminated zeolitic catalyst has a measured first-orderconstant, k_(cum), for the alkylation of benzene with propylene to formcumene, of at least 3 cm³/s g.
 6. The method of claim 1, wherein theorganic dibasic acid comprises at least one of oxalic acid, malonicacid, glutaric acid, adipic acid, maleic acid, fumaric acid, tartaricacid, ethylene diamine tetra-acetic acid, and mixtures thereof.
 7. Themethod of claim 1, wherein the zeolitic catalyst comprises at least oneof a silica-alumina and an alunimosilicate.
 8. The method of claim 1,wherein the contacting is at a temperature in the range from about 65°C. to about 90° C. and is performed for a duration of between 0.5 and1.5 hours.
 9. The method of claim 1, wherein the zeolitic catalystcomprises at least one of zeolite Beta, ZSM-5, ZSM-22, ZSM-23, MCM-22,and MCM-49.
 10. The method of claim 1, wherein the acidic zeoliticcatalyst comprises high performance beta zeolite and wherein theselectively dealuminated zeolitic catalyst has a measured first-orderrate constant, k_(cum), for the alkylation of benzene with propylene toform cumene, of at least 4 cm³/s g.